1. Field of the Invention
The disclosure relates to the field of vacuum cleaners. More specifically, the disclosure relates to vacuum cleaners having removable filters.
2. Description of the Related Art
Vacuum cleaners are notoriously dusty and dirty, requiring some method to separate the dust and the dirt from the exhaust air. Hence, filters are commonly used to perform this separation function. There often is a need to remove and re-attach the filter, for example when cleaning the filter or replacing it with a new filter. With the type of vacuum cleaner known as wet and dry vacuum cleaners, the filter is also often removed when the vacuum cleaner is used to suction liquids. Thus, special structures accompany a typical wet/dry vacuum cleaner to accommodate removing and replacing the filter.
Typically, a suction system with a motor creates the vacuum and is mounted in a lid that is removably attached to a collection drum for receiving the vacuumed materials. A portion of the lid, herein termed a mounting assembly, extends at least partially downward into the drum and mounts a filter support assembly, such as commonly known as a “cage,” that generally covers a vacuum intake to the suction assembly in the lid. The cage is composed of a series of ribs, with a large percentage of open surface area. The ribs support the filter and prevent radially inward collapse of the filter during operation. The lid suctions external air or water through a hose into an opening in the drum or lid, so that water or dirt is deposited into the drum. Remaining material, mainly air, then flows radially inward through the filter for removal of dirt and debris. The filtered air then continues through the filter support assembly into a suction impeller in the lid, and then is exhausted from the vacuum cleaner.
In many such systems, the entire filter body is attached to the mounting assembly by a mounting flange removably attached to the mounting assembly. The filter is inserted over the cage, and a mounting flange of rigid material, such as plastic, is attached to the cage or mounting assembly and used to compress or “sandwich” the filter between the flange and the mounting assembly. The compressive force on the entire filter body and its filter element is the primary force used to seal the filter to the vacuum cleaner and prevent unwanted leakage into the impeller.
Experience has shown that operators have difficulty determining how much compressive force to use on the filter body, because such installation includes compressing the filter element as well. At times, operators use too little force and achieve an inadequate seal, thus allowing leakage of fine dust, resulting in wear on the internal vacuum motor, impeller, and other internal structures. At other times, operators apply too much force and crush the filter or strip the attachment threads, causing repair or replacement of parts. Further, the compressive force can vary without notice to the user, depending, for example, on whether the filter media has been exposed to moisture as is typical in a wet/dry vacuum cleaner.
Therefore, there remains a need for an improved filter design and system for mounting and sealing the filter in such a vacuum cleaner.